Abstract: In this paper, single-pass multi-layer thin-walled specimens of 2Cr13 martensitic stainless steel were fabricated by arc wire additive manufacturing system with cold metal transition (Cold metal transfer, CMT) technology. The effects of different interlayer temperatures (100 ℃, 150 ℃ and 200 ℃) on the surface forming, microstructure evolution and mechanical properties of thin-walled specimens were studied. The results showed that higher interlayer temperature would increase the overall temperature of the forming parts, worsen the heat dissipation, increase the existence time of the molten pool ,enhance the fluidity of the molten metal, and ultimately result in the deterioration or even collapse of the surface of the forming parts. Due to the repeated heating and cooling process, the middle part microstructure of the forming parts were mainly composed of extremely slender lath martensite, accompanied by a small amount of ferrite and carbides precipitated along the ferrite grain boundary. Near the remelting zone, due to the thermal action of the molten pool, the martensite structure would be overheated and undergone phase transformation to form dense ferrite. With the decrease of interlayer temperature, the grain size of the forming parts was smaller and the distribution was more uniform. In addition, the dispersed carbides on the ferrite grain boundary hindered the dislocation movement. The combined action of the two mentioned above made the microhardness and tensile strength increase with the decrease of interlayer temperature, and the elongation of the tensile specimen was also enhanced at the same time. The tensile fracture forms were all ductile fracture, with the decreasing of interlayer temperature, the fracture size became larger and larger, and the dimple became deeper and deeper in the same sampling direction.